An injector for inserting an intraocular lens into an eye is disclosed, comprising a main body (10) and a plunger (50). A guide element (30) is connected to the distal end of the plunger to laterally guide the plunger during movement along a longitudinal axis (L). The distal end of the guide element has a fastening structure for fastening a plunger needle to the guide element. A radial guide pin (40) is held in aligned radial bores of the guide element and of the plunger and extends into a longitudinal slot (17) of the main body, so as to prevent twisting of the plunger relative to the main body and to secure the guide element to the plunger. A retaining element (24) in the form of a spring-biased sphere interacts with a running surface on the perimeter of the plunger, the running surface having a variable radial distance from the longitudinal axis so as to cause an axial resistance force which depends on the axial position of the plunger.